Recent studies which have measured physical activity objectively show that few primary school-age children in the UK meet public health recommendations for physical activity of one hour of moderate-vigorous intensity physical activity (MVPA) daily [1
]. Low levels of physical activity can be expected to have deleterious effects with substantial public health impact [5
]. Physical activity is even lower than UK averages for children for some ethnic minority groups [6
], lower in girls than boys, and lower among the overweight and obese [4
]. Recent UK studies have shown that objectively measured physical activity declines, and objectively measured sedentary behaviour increases before adolescence [4
]: these changes in mid-late childhood are also more marked among girls, the overweight and obese, those with lowest levels of physical activity [4
], and predict subsequent changes in body fatness [8
]. Moreover, recent evidence has shown that of all the periods from birth to late adolescence, mid-late childhood in the UK (around the ages of 7-11 years) is characterised by the greatest incidence (emergence of new cases) of obesity [9
], and the greatest degree of excessive weight gain among those who do not become obese [10
]. This recent evidence suggests that mid-late childhood (towards the end of the primary school years in the UK) should be considered a priority in interventions aimed at promoting physical activity, preventing future obesity, and/or promoting a reduction in sedentary behaviour.
Systematic reviews of interventions to promote physical activity in school-age children suggest that physical activity is modifiable to some degree [11
], and physical activity promotion is helpful to obesity prevention [13
]. Physical activity is potentially very flexible in children, influenced largely by factors in the physical and cultural environment which are at least partly modifiable [15
]. Making environmental changes which are conducive to physical activity is a logical response to concerns over the low levels of physical activity of children. However, systematic reviews on interventions to promote physical activity in childhood have noted many limitations in the evidence, and most interventions have had only modest and short-term impact on physical activity or obesity risk [11
]. The belief that increased physical activity will reduce obesity risk has even been questioned [15
]. The evidence on interventions to promote physical activity therefore suggests that novel approaches to physical activity promotion in childhood are required: these should aim to have more marked effects on physical activity, and should aim to be more sustainable than interventions which have been typical in the past.
Dog ownership is a significant societal factor that may be used to encourage and sustain health behaviour change at individual and population level [18
]. Many UK households own dogs, and it is unlikely that they are all walked on a frequent and regular basis, thus providing a target group for interventions to promote physical activity. It has been suggested that the pet dog is a potentially valuable but neglected resource for physical activity promotion in children and adults [18
], providing opportunities with wide population 'reach'. In Scotland for example there are approximately 800,000 dogs and 360,000 children of primary-school age. Approximately 20-30% of households in many western countries own pet dogs (19,). In the UK approximately 22-24% [19
] of all households own a pet dog, but dog ownership is even more common among households with children [20
]. A number of cross-sectional observational studies, including some studies which have measured physical activity objectively, have shown slightly higher physical activity levels for adults who walk their dogs regularly and have reported a tendency for adult dog owners to meet physical activity recommendations more commonly than non dog-owners [21
]. Recent UK evidence suggests that, in the absence of any specific intervention, children typically are slightly more physically active if they own a dog [24
]. However, one Australian study examined dog walking in children: only 23% of 5-6 year olds and 37% of 10-12 year old children ever walked with their dog [25
]. Dog ownership has been associated with lower weight status and increased physical activity in some sub-groups within studies, but not all sub-groups [25
]. A recent study across the city of Liverpool in the UK found that 59% of 9-10 y olds who owned dogs reported some involvement in walking their dogs, but only 34% reported walking their dogs daily (unpublished, Westgarth et al.). Recent analyses of the large UK birth cohort 'ALSPAC' (the Avon Longitudinal Study of Parents and Children) provided no evidence that 7 year old children whose family owned a dog were less likely to be overweight/obese [28
]. One intervention study which used dogs to promote physical activity [29
] was promising, but was an obesity treatment trial in adults only, and so is of limited relevance to public health interventions for children and their families.
In summary, dogs are present in a high proportion of households, and have the potential to increase child and adult physical activity [18
], but have not been used for this purpose to any great extent to date. Promotion of more walking and play with the dog could be a useful strategy to promote family physical activity. At this stage however, evidence is lacking as to whether and how interventions with families and their dogs can be used to promote physical activity. There is sufficient evidence from observational studies now to conclude that dogs and their owners have potential to walk more, and intervention studies are now justified.
Concerns over declining physical activity in mid-late childhood suggest that this may be a useful period of the lifecycle to intervene to promote physical activity, or at least to mitigate the reduction in physical activity which occurs at this time. Most interventions to date have been school-based [11
]. There is much less evidence from interventions in other settings, including the family/home [30
], despite the evidence that the home environment is a consistent predictor of objectively measured physical activity level in studies of mid-late childhood [30
], and the suggestion from a recent systematic review that the home/family may be the most promising setting for promoting child physical activity [11
]. Approaches aimed at promoting physical activity should be developed and evaluated using a robust framework [33
], should have a theoretical basis [33
], and should be tested rigorously using randomised controlled trials (RCT; 33).
The current study, Children, Parents, and Pets Exercising Together (CPET) therefore aims to develop and evaluate a family-based physical activity promotion intervention based on using the pet dog to increase physical activity and reduce sedentary behaviour for the family. The intervention is theory-driven and the development of the study has followed advice in the UK Medical Research Council Framework on the Development and Evaluation of Complex Interventions [33
], including the advice to carry out an 'exploratory trial' before carrying out a larger scale, longer-term, more 'definitive trial'. The present exploratory trial is therefore the first step along the path towards a definitive trial, leading to at least one more RCT, drawing on the UK Medical Research Council Framework and other guidance such as 'RE-AIM' [35
]. The study should also inform the development of future public health interventions involving dogs in other populations (e.g. in adults, in older adults; 18). The specific research questions being asked in CPET are listed in Table .
Research questions to be addressed in CPET study